Understanding the regulatory elements controlling brain development is a crucial and extremely exciting area of investigation. One of the most attractive developmental neurobiological system currently under study is myelination, and the myelin proteolipid protein gene is an excellent model gene within this system. Its expression is tightly developmentally regulated; it is expressed in brain as a major component of a single cell type; there are specific mutants with well-defined alterations in this gene. Even conservative amino acid mutations in this protein are devastating to normal brain development. Our fundamental hypothesis is that there are multiple regulators of this gene, and that unique regulatory changes occur as a consequence of specific mutations, within this gene and in other myelin-specific genes. We propose to isolate and characterize DNA-binding proteins that regulate this myelin-specific gene and characterize how these regulators are themselves affected in dysmyelination. In studies on several dysmyelination mutants, we will determine which changes in PLP gene expression are specific to PLP gene mutations, and which occur whenever myelin biosynthesis is disrupted. We will test our hypothesis that mRNA destabilization plays a role in dysmyelination, by determining mRNA stability in these mutants. In order to pursue an in-depth understanding of the regulation of PLP gene expression, we will clone cDNAs of PLP gene DNA-binding proteins and study the regulation of their expression, developmentally and in mutants. We will test the hypothesis that protein kinase C, an important mediator of signal transduction, is involved in PLP gene expression, and that alterations in gene expression in mutants can be mediated through changes in protein kinase C activity. With the completion of the proposed studies, we will be able to define how this gene is normally expressed, and how abnormalities in its expression are controlled. We will have a battery of tools with which to study the bank of genes that regulate PLP gene expression, and we will have an deeper understanding of the role of at least one controlling element, protein kinase C.